Web aligning apparatus



April 7, 1970 F. J. GUEST 3,

WEB ALIGN INGAPPARATUS Filed May 29, 1968 5 Sheets-Sheet 1 FRANK J. GUEST ATTORNEY April 7, 1970 F. J. GUEST WEB 'ALIGNING APPARATUS 5 Sheets-Sheet 2 Filed May 29, 1968 FRANK J. GUEST ATTORNEY April 7, 1970 F. .1. GUEST A 3,504,334

WEB ALIGNING APPARATUS Filed May 29, 1968 5 Sheets-Sheet 5 FIG.

INVENTOR FRANK J. GUEST ATTORNEY April 7, 1970 F. J. GUEST 3,504,834

WEB ALIGNING APPARATUS Filed May 29, 1968 5 Sheets-Sheet 4 'INVENTOR FRANK J. GUEST BY I ATTORNEY April 7, 1970 F. J. GUEST WEB ALIGNING APPARATUS 5 Sheets-Sheet 5 Filed May 29, 1968 ATTORNEY United States Patent 3,504,834 WEB ALIGNING APPARATUS Frank J. Guest, Brevard, N.C., assiguor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed May 29, 1968, Ser. No. 733,178 Int. Cl. B65h 23/12 US. Cl. 22622 9 Claims ABSTRACT OF THE DISCLOSURE An improved apparatus for obtaining maximum lateral divergence of a moving web without surface abrasion of the web by passage over spaced multiroll assemblies along an S-shaped path, wherein the roll assemblies are adapted with means for inclining the rolls transversely about the roll assembly axes thereby causing the web to follow a true helical path.

SUMMARY OF THE INVENTION The apparatu efiFects lateral displacement of a traveling web without accompanying frictional abrasion of the web surface while in contact with guide members. In general, the apparatus has a web aligning unit comprismg:

(a) Two multiroll assemblies arranged parallel and in tandem on a pivotal carrier, each roll assembly composed of a plurality of straight rollers equally paced about the central axis of the assembly, the first multiroll assembly including a substantially fixed entrance roller for receiving an incoming web, and the second multiroll assembly for receiving the web from the first assembly and directing it to an outgoing means,

(b) A carrier pivoted about an axis intersecting the rotational axis of the entrance roller at one end,

(c) An actuator responsive to a web edge sensor for pivoting the carrier back and forth a predetermined amount thereby laterally displacing the second multiroll assembly in the direction of the desired correction, and

(d) Means for inclining the rollers of the first and second multiroll assemblies transversely in response to pivotal movement of the carrier whereby the rollers of the first assembly are inclined to change the angular direction of travel of the incoming web and thereby follow a true helical path beginning with the entrance roller and following through to the point where the rollers of the second assembly are inclined inversely with the first assembly to restore by way of a true helical path the travel of the web to its original direction.

An alternative embodiment of the aforementioned apparatus lends itself ideally as a traversing unit for continuous winding of thin films into mill roll packages, in order to compensate for gauge variations in the web being wound so that an accurately wound roll of web with aligned edges will result.

DESCRIPTION OF THE PRIOR ART It is well known that movement of a long length web over roll guides, or the like, results in the web varying laterally from its true path of travel.

In the manufacture of coated papers, printed matter, and more particularly in precision coating of photographic film base, magnetic tape and the like, accurate registration and alignment of the moving web relative to the coating and winding equipment is important for obtaining high quality results.

In general, most commercial black-and-white photographic film structures are composed of a clear polymeric film base, various sublayers, a layer of photosensitive emulsion, and an overcoat to protect the photosensitive emulsion. All layers are of predetermined uniform thickness and are applied by precision coating techniques. It is during the coating of these layers that web movement must be smooth, steady and alignment accurate. Any sudden movement of the web such as might occur during lateral adjustment is sufiicient to disrupt the operation and cause nonuniformities. Moreover, it i generally the practice to coat photographic film full width leaving an uncoated narrow stripe or band at each edge. Thus, a slight lateral shift or misalignment of the web will usually result in loss of costly coating material over the edge and subsequent contamination of the guide rollers. The problem becomes especially troublesome following a web splice sequence, when web misalignment is most likely to occur.

When layers are being coated on both sides of the web, extraordinary web handling procedures must be considered because the slightest sliding movement, even over highly polished guide surfaces is sufiicient to scratch the coated surfaces and result in impairment of the final product.

Most conventional web aligning apparatus can be categorized as either rapid or slow response devices. The rapid response devices are capable of nearly instantaneous correction; however, they tend to overcorrect, are somewhat inaccurate, and subject the web to localized stresses. The slow response types, on the other hand, generally are more accurate but involve prolonged intervals to restore the web to equilibrium conditions. Another serious disadvantage of the latter type is that during the correction interval substantial quantities of product can be processed containing the imperfection arising from the error being overcome and therefore may have to be downgraded or rejected.

Many attempts have been made to provide web handling apparatus which overcome the aforementioned difficulties. Some practicable machines of the prior art are described in UJS. 2,513,927, to G. H. Farrington and US. 3,265,272, to D. S. Smith. In US. 2,513,927, Farrington describes a web aligning apparatus featuring four parallel rolls journaled at the corners of a rectangular frame over which a moving web travels. The two lower rolls are substantially fixed while the two upper rolls are mounted at one end for limited angular movement. Corrective adjustment of the moving web is made by a slight angular inclination of the upper rolls either manually or by mechanical means. The inclination causes a change in the travel length between the edges of the web for which the web compensates by laterally shifting in the direction that equalizes the edge distances. Lateral adjustment of the web is accomplished relatively rapidly and smoothly with the Farrington apparatus, but unfortunately it is not suitable for use with photographic films because of the sliding movement along the inclined rolls.

The apparatus disclosed in US. 3,265,272 overcomes some of the aforementioned difficulties by an automatic device which comprises self centering receiver and delivery roller assemblies. An important feature of the apparatus is concerned with minimizing abrasion of web surface by passage over a plurality of spaced spherical rollers which are mounted on longitudinal shafts of the roller assemblies. These spherical rollers are capable of rotation in an inclined direction and thereby provide approximate helical paths of travel for the lanes of web making contact during lateral displacement. Functionally, the inclinable rollers tend to minimize the angular differences between the roller assemblies and the traveling web and thus reduce the lateral frictional sliding during corrective adjustment. Since the lateral movement only follows an approximate helical path, some sliding action takes place at the point Where the incoming Web enters the receiver roller assembly.

The nature of this prior aligning assembly is such that all the web contacting rollers automatically shift to a new correct position simultaneously. As a consequence, the incoming web on making contact with the first set of rollers experiences a sudden unstable tracking condition which can only be corrected by lateral sliding. As the web contacts successive rollers, the degree of instability decreases and the lateral movement takes on a nearly helical path.

A major advantage of the apparatus of applicants invention is that it is a compact web centering apparatus capable of making rapid, accurate, maximum corrective web position adjustment, along a true helical path, without frictional surface abrasion, while the Web is moving or in a standstill condition. Another advantage is that the apparatus enables one to control lateral traversing of a moving web continuously during a coating and winding operation.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an elevation of a multiroll assembly or cage showing the S-shaped path taken by the moving web.

FIG. 2 is a plan view of the web aligning apparatus showing the pivot about which the second multiroll assembly is displaced laterally during a corrective action and the actuator device for effecting displacement.

FIG. 3 is a section taken along the line 33 of FIG. 2 showing the mid-position roller supports for bowing the rollers during a large corrective movement to maintain the cage generally cylindrical.

FIG. 4 is a partial elevation of the first multiroll assembly taken along line 44 of FIG. 2 as seen by the incoming web.

FIG. 5 is a partial end view of the second multiroll assembly taken along line 55 of FIG. 2 showing the roller journal mounting and Web edge sensing mechanism.

FIG. 6 is an elevation showing a general, arrangement of the modified apparatus in a film processing line positioned upstream of a mill roll windup station.

FIG. 7 is a diagrammatic view of pneumatic web edge sensors and traversing control circuitry of the apparatus.

Referring to the figures, the aligner apparatus is composed of four major parts or units, a stationary frame 1, a ivotal carrier 2, and multiroll assemblies or cages 3 and 4.

Frame 1 is composed of structural steel with weldments and comprises side supports 5 and 6 to which are attached horizontal brackets 7, 8, 9 and 10. These brackets are provided with smooth fiat surfaces and serve as supports for the carrier 2. Likewise, carrier 2 is a structural steel box-shaped weldment having uprights 11 and 12 which are rigidly held apart by horizontal spacers 13 and 14. One corner of upright 12 interfits with a stationary pivot shaft 15 which is attached to bracket 7. Carrier 2 pivots about this shaft which hereafter will be described as pivot axis 16. At the other corners, carrier 2 is supported on rollers 17, 18 and 19 which freely roll on brackets 8, 9 and 10, respectively. These are ordinary commercially obtainable cam followers attached by threading to modified mounting brackets 20' that are fastened suitably to the uprights 11 and 12. The mounting surfaces of brackets 20 are obliquely angled to align the rotational axis of each roller on a radial line from pivot axis 16.

Between uprights 11 and 12 are multiroll cages 3 and 4 over which a web 21 is guided through an S-shaped path. Both cages are mounted parallel and in tandem with each other and are substantially identical in structure and function. In the interest of simplifying the discussion, only cage 3 is described in detail; however, it is understood that the description pertains to both except where differences are noted, As shown, cage 3 is composed of three slender, freely rotatable tubes or rolls 23 which are spaced apart equidistant about the central axis of the cage. Theoretically, cage 3 may be adapted with any number of rolls 23 with good effect; however, in the preferred embodiment a minimum of three are utilized for reasons of economics and mechanical simplicity. As best shown in FIG. 5, rolls 23 are modified by reduced end sections that engage the inner races of self-aligning antifriction bearings 24 and 25. At the upright 12 end the outer races of bearings 24 are retained in matching recesses while at the other end of the rolls 23, the outer races of antifriction bearings 25 are retained in pivot plates 26 and 27. Pivot plates 26 and 27 are adapted with roll pins or stub shafts 28 and 29 which are rotatably journaled in sleeve bushings in upright 11. It is noted that the respective centerline axis of stub shaft 28, 23 coincides with the central axis of the cage.

A connecting rod 30 is operatively linked to plates 26 and 27 such that a clockwise rotation of plate 27 induces counterclockwise rotation of plate 26. Thus a rotational movement of the plates 26 and 27 displaces the rolls 23 about the central axis of each cage at the upright 11 end. Since the rolls 23 are essentially fixed at the upright 12 end, the displacement of the rolls 23 causes the rolls to be inclined at some angle relative to the direction of travel of the web 21. The magnitude and direction of the inclination serves to alter tracking either to the right or left.

Movement of the cages 3 and 4, that is, pivoting of plates 26 and 27 is accomplished by a linear pneumatic actuator 31 which is mounted in a conventional manner to a bracket 32 and attached to stationary side support 5. The movable rod of actuator 31 is affixed to a rod end 30A that, in turn, is pinned to one end of a coupling link 33. The other end of link 33 is afiixed to a rigid drive post 34 which is attached at its base by threaded fasteners to upright 11. Actuator 31 is a standard commercial item similar to a series 501 unit manufactured by the Conofiow Company.

Referring to FIGS. 4 and 5, ball joint 35 is shown at tached to pivot plate 26 of cage 3 at a point directly above stub shaft 28. This joint is operatively connected to a stationary socket block 36 which is essentially an open vertical slot into which the ball element of joint 35 is engaged. The block is composed of a low friction polymeric material to accommodate for any relative movement of the joint 35 as pivot plate 26 rotates. Socket block 36 is suitably attached to a stationary anchor post 37 which post, in turn, is secured by threaded fasteners to bracket 10.

Thus plaate 26 of roll cage 3 is partially constrained by ball joint 35 and 36, and a shift of carrier 2 is accompanied by transverse displacement of the rollers 23 relative to the central axis of cage 3 except for the roll on a direct line from the joint 35. The partial constraint brought about by joint 35 causes the roll to remain substantially stationary. This roll is the first guide member making contact with the incoming web and is hereafter referred to as entrance roll 22. Once the entrance roll 22 axis is aligned perpendicular to the direct travel of the moving web, it remains in the proper alignment regardless of the amount of correction being imposed on the web downstream from the point. This alignment is made upon completion of the machine.

As will become apparent, marked skewing of rolls 23 results in a change of the cylindrical geometry of the cages; that is, the circumferential surface of each cage transforms into a hyper-boloid envelope with the characteristic saddleback profile. From a processing viewpoint, the aforementioned condition is undesirable for the saddleback surface subjects the web to uneven tension and subsequent wrinkling.

In normal operation the magnitude of skewing of the rolls 23 is relatively small; therefore, formation of the hyperbolic envelope can be controlled by bending or flexing the rolls 23 slightly at the midpoint by means of stationary midroll deflectors 38 and 39. As best shown in FIG. 3, deflectors 38, 39 are each provided with dualwheel rollers 40 which are journaled in guides 41 and act against rolls 23. Each guide 41 is aflixed to a pivot block 42 by means of a threaded stud 43 which also serves for precision adjustment of the rollers 40. A pivot shaft 44 extends through pivot block 42 and engages a stationary pivot bracket 45. This bracket 45 is attached to a rigid transverse brace 46 which is separate and independent of any movements of the adjacent cage and is connected by conventional fasteners at the ends to uprights 11 and 12. Precision adjustment of rollers 40 relative to the rolls 23 in each cage is made while both cages are in the zero correction position; i.e., at a time when the axes of rolls 23 are parallel to the central axes of the cages and substantially perpendicular to the direction of travel of web 21.

Once the adjustment of deflectors 38 and 39 is preset, cage rolls 23 upon skewing during a corrective movement of the cages will be forced against and restrained by the rollers 40. The restraint is sufficient to flex the rolls 23 slightly. In applications involving handling of wide sheet material; that is, in excess of 60 inches, a recognizable bow will be evident of the roll 23. The bowed effect tends to maintain the diameter of the cage at the midregion and counteract the saddleback shape.

Referring back to FIG. 5, the position of the moving web 21 is continuously monitored by a closed loop pneumatic sensing system which includes a position sensor unit 47 mounted to a bracket 48 extending from side support 5. Unit 47 is a standard commercial item more commonly known as a type CP position transmitter device manufactured by the Foxboro Company, Foxboro, Mass. The output shaft of unit 47 is affixed with a sensing arm 49 that physically contacts and is responsive to changes in the edge of the moving web 21.

A movement of arm 49 causes unit 47 to transmit a pneumatic pilot pressure signal to a commercial flow con-- troller device (not shown) which governs the pressurized fluid supply to actuator 31. Like sensor 47, the flow controller is a commercial item which can be purchased from the Moore Products Company of Pennsylvania.

In operation the preferred embodiment can readily handle webs at least 45 inches wide. A polymeric web traveling in excess of 120 feet per minute man be laterally displaced up to four inches maximum within i fl g of an inch from a predetermined position.

In the manufacture of thin gauge film such as the kind used for packaging, electrical insulation and the like, gauge thickness nonuniformities often appear as continuous narrow bands of slightly greater thickness that are a source of considerable difliculty during winding into mill roll packages. It is important that the film be wound under controlled tension conditions in order to produce a stable package. The presence of a gauge band usually results in a rapid buildup of the packages in the vicinity of the variation at the expense of the remaining portions of the web. Unless measures are taken to compensate the lay- 'down of a gauge band, a highly unstable package is formed which usually results in the layer telescoping during handling.

An alternative embodiment of the present invention provides a very satisfactory apparatus for compensating the laydown. Apparatus for controlling the oscillation of the guide frame is illustrated in FIGS. 6 and 7.

In FIG. 6, the essential features of the web aligner apparatus are intact except for the edge sensor unit 47, bracket 48 and sensing arm 49. These components are removed and replaced by the following components.

A pair of spaced web edge sensing devices 50 and 51 are positioned at a suitable distance below the multiroll cage 4 on the same plane. Depending on the kind of web material being processed, any type of edge detector can be used. For example, optical, radiation, inductance, capacitance type devices can be used with good effect. In

the instance where thin gauge transparent polyester film is being handled, pneumatic noncontacting sensors are preferred sensors. Devices 50 and 51 are stock items which can be purchased under the trade name of Dynaguide No. 21510 by General Precision Company of Morton Grove, Ill. These units are fixedly mounted to the stationary process equipment framework which also sup ports the aligner apparatus.

As shown in FIGURE 6, sensor devices 50 and 51 are adjusted a preset distance apart which is equal to the web width plus the lateral displacement or traverse distance d. For most situations the total lateral displacement d can be anywhere from four to ten inches. In the present case, a traverse distance d of five inches is preferred. If additional lateral displacement is required, it is necessary to modify the aligner apparatus by increasing the centerline spacing e between roll cages 3 and 4.

The inputs of devices 50 and 51 are connected to a supply of regulated low pressure air which forms a fluid stream across an air gap that can be interrupted by the traveling web 21. In the non-interrupted condition, the fluid stream is conveyed to a controller 52 which contains fiuidic devices for selectively switching a source of regulated high pressure air to a double acting pneumatic actuator 53 which pivots the roll cages 3 and 4. The high pressure air supply input line is directly connected to the controller 52 and from that to both ends of the pneumatic actuator 53. Actuator 53 may be a standard reversing series 50 No. B-S lXW-3 unit manufactured by the Comflow Corporation, Philadelphia, Pa.

Referring now to FIGURE 7, the internal workings of suitable controller 52 are composed of two fluidic or/ nor gates 54 and 55, a bistable fluidic flip-flop fluid amplifier 56 and a pilot-controlled air valve 57. The gates 54, 55 and amplifier 56 are commercial fluid logic devices made by the Corning Glass Works of Corning, NY. Likewise, valve 57 is a N0. 7986 Mt-inch unit manufactured by the Alkon Products Corporation of Hawthorne, NJ. The inputs of gates 54 and 55 are connected on one side to a source of low pressure (1.5 p.s.i.g.) regulated air, and on the other side to the outputs of sensor devices 50 and 51. Similarly, amplifier 56 is connected to a source of low pressure (3.0 p.s.i.g.) regulated air and the outputs of gates 54 and 55. The dual outputs 60- and 61 of amplifier 56 are connected to opposite ends of the pilot portion of air valve 57. The high pressure air portion of the valve is connected to the air supply line on the input side and to either end of actuator 53. Needle valves 58 and 59 are connected to the exhaust ports for speed control adjustment.

In operation, after the traveling web 21 is threaded around the multiroll cages 3 and 4, and attached to the windup core, the following prerun adjustments and settings are made. Sensors 50 and 51 are checked for predetermined spacing in accordance with the amount of lateral displacement desired in the traveling web. Input air supply pressures to the gates 54 and 55 are set at 1.5 p.s.i.g. and to the amplifier 56 at 3.0 p.s.i.g. At this point actuator 53 is activated by introduction of high pressure (about p.s.i.g.) into pilot valve 57; the apparatus commences to traverse the web 21 which by now is traveling at process speed. In the drawings, traveling Web 21 is shown in the maximum displacement to the right and interrupting the fluid stream in sensor 51.

Normally, in the opened condition, sufficient air flow moves across the gap to influence the supply air of the fluidic gate 55 which causes the stream to be deflected out of the exhaust passage 62. In the closed condition, the air flow across the gap is terminated and the fluid stream in gate 55 switches to the input line 64 leading to amplifier 56. The lateral air flow flips the supply air in the amplifier 56 to output 60. This output, in turn, is connected to one end of the pilot valve 57, and is sutficient to shift the spindle and, thereby, switch the high pressure air supply to the actuator 53. In FIG. 7, the pilot spindle is shown in the position just before being shifted by the output 60 of amplifier 56.

It is noted that amplifier 56 is a bistable type fluidic device which requires positive lateral air flow to deflect supply stream from one output to the other. In other words, when the stream is shifted into output 60 and the lateral input removed, the fluid stream remains in the shifted position until acted upon from the opposite lateral branch. As a consequence, actuator 53 remains energized and web 21 continues to track toward edge sensor 50. The velocity of the traversing movement is regulated by adjustment of needle valves 58 and 59 which vent the unpressurized side of the actuator.

The web continues to track laterally until the edge interrupts the air flow of sensor 50. At this time, input 63 is removed and gate 54 transmits a fluid signal into input 65, which deflects the amplified stream to output 61. Since output 61 is connected to the opposite end of valve 57, the air supply is switched and actuator 53 is reversed. On the return stroke, needle valve 59 is venting the unpressurized air ahead of the actuator piston.

The above sequence continues repeatedly until a mill roll of predetermined size is formed. At such time, the high pressure air is either manually or automatically cutoff, the full roll is removed and replaced with a new core.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A Web aligning apparatus having:

(A) guide rolls for feeding a web to a web aligning unit comprising:

(a) two multiroll asemblies mounted in parallel and in tandem to provide an S-shaped path for a moving web, each roll assembly being composed of a plurality of web rollers equally spaced about the central axis of the assembly and having one end fixed and the other end movable about said axis so that the web rollers can be inclined with respect to the axis, the entrance roller thereof being maintained in a position perpendicular to the path of the web.

(b) a carrier for said assemblies pivoted about an axis intersecting the axis of said entrance roller at the fixed end;

(c) an actuator responsive to a web sensing means for pivoting the carrier a predetermined amount about the axis of the pivot thereby displacing the second multiroll assembly in the direction of the desired correction; and

(d) means for inclining the Web rollers of the first and second assemblies simultaneously in response to the pivotal movement of the carrier, whereby the Web rollers of the first assembly are inclined to change the angular direction of travel of the incoming web, and thereby follow a true helical path beginning with the passage of the web over the entrance web roller downwardly and around the remaining web rollers, then upwardly to the receiving web roller of the second assembly where the web rollers of the second assembly are inclined inversely with respect to the first assembly to restore by way of a true helical path the travel of the web; and

(B) guide rolls for removing the web from the web aligning unit.

2. An apparatus according to claim 1 having:

(e) pneumatic means connected to the carrier for pivoting said carrier.

3. An apparatus according to claim 1 having deflecting means for flexing the Web rollers near their midpoints.

4. An apparatus according to claim 1 having deflecting means mounted on the carrier comprising a pair of pivotally mounted wheels for each web roller for flexing each web roller near its midpoint.

5. An apparatus according to claim 1 where the pivot is near one corner of the carrier and the other corner of the carrier has supporting rollers that contact with supporting brackets on the frame.

6. A web aligning unit comprising:

(a) two multiroll assemblies mounted in parallel and in tandem to provide an S-shaped path for a moving web, each roll assembly being composed of a plurality of web rollers equally spaced about the central axis of the assembly and having one end fixed and the other end movable about said axis so that the web rollers can be inclined with respect to the axis, the entrance roller thereof being maintained in a position perpendicular to the path of the web;

(b) a carrier for said assemblies pivoted about an axis intersecting the axis of said entrance roller at the fixed end;

(c) an actuator responsive to a Web sensing means for pivoting the carrier a predetermined amount about the axis of the pivot thereby displacing the second multiroll assembly in the direction of the desired correction; and

(d) means for inclining the web rollers of the first and second assemblies simultaneously in response to the pivotal movement of the carrier, whereby the web rollers of the first assembly are inclined to change the angular direction of travel of the incoming web, and thereby follow a true helical path beginning with the passage of the web over the entrance Web roller downwardly and around the remaining web rollers, then upwardly to the receiving web roller of the second assembly Where the web rollers of the second assembly are inclined inversely with respect to the first assembly to restore by way of a true helical path the travel of the web.

7. A unit according to claim 6 having:

(e) pneumatic means connected to the carrier for pivoting said carrier.

8. A unit according to claim 6 having deflecting means for flexing the Web rollers near their midpoints.

9. A unit according to claim 6 having deflecting means mounted on the carrier comprising a pair of pivotally mounted wheels for each web roller for flexing each web roller near its midpoint.

References Cited UNITED STATES PATENTS 1,754,629 4/1930 Kirk 226-23 2,607,588 8/1952 Morey 226-23 2,807,465 9/ 1957 Newell 226l6 3,326,435 6/1967 Shelton 226-22 ALLEN N. KNOWLES, Primary Examiner US Cl. X.R. 226l97 

